/*

 * Copyright (C) the libgit2 contributors. All rights reserved.

 *

 * This file is part of libgit2, distributed under the GNU GPL v2 with

 * a Linking Exception. For full terms see the included COPYING file.

 */

#ifndef INCLUDE_git_odb_backend_h__

#define INCLUDE_git_odb_backend_h__

#include "common.h"

#include "types.h"

/**

 * @file git2/backend.h

 * @brief Git custom backend functions

 * @defgroup git_odb Git object database routines

 * @ingroup Git

 * @{

 */

GIT_BEGIN_DECL

/*

 * Constructors for in-box ODB backends.

 */

/**

 * Create a backend for the packfiles.

 *

 * @param out location to store the odb backend pointer

 * @param objects_dir the Git repository's objects directory

 *

 * @return 0 or an error code

 */

GIT_EXTERN(int) git_odb_backend_pack(git_odb_backend **out, const char *objects_dir);

/**

 * Create a backend for loose objects

 *

 * @param out location to store the odb backend pointer

 * @param objects_dir the Git repository's objects directory

 * @param compression_level zlib compression level to use

 * @param do_fsync whether to do an fsync() after writing

 * @param dir_mode permissions to use creating a directory or 0 for defaults

 * @param file_mode permissions to use creating a file or 0 for defaults

 *

 * @return 0 or an error code

 */

GIT_EXTERN(int) git_odb_backend_loose(

	git_odb_backend **out,

	const char *objects_dir,

	int compression_level,

	int do_fsync,

	unsigned int dir_mode,

	unsigned int file_mode);

/**

 * Create a backend out of a single packfile

 *

 * This can be useful for inspecting the contents of a single

 * packfile.

 *

 * @param out location to store the odb backend pointer

 * @param index_file path to the packfile's .idx file

 *

 * @return 0 or an error code

 */

GIT_EXTERN(int) git_odb_backend_one_pack(git_odb_backend **out, const char *index_file);

/** Streaming mode */

typedef enum {

	GIT_STREAM_RDONLY = (1 << 1),

	GIT_STREAM_WRONLY = (1 << 2),

	GIT_STREAM_RW = (GIT_STREAM_RDONLY | GIT_STREAM_WRONLY),

} git_odb_stream_t;

/**

 * A stream to read/write from a backend.

 *

 * This represents a stream of data being written to or read from a

 * backend. When writing, the frontend functions take care of

 * calculating the object's id and all `finalize_write` needs to do is

 * store the object with the id it is passed.

 */

struct git_odb_stream {

	git_odb_backend *backend;

	unsigned int mode;

	void *hash_ctx;

	git_off_t declared_size;

	git_off_t received_bytes;

	/**

	 * Write at most `len` bytes into `buffer` and advance the stream.

	 */

	int (*read)(git_odb_stream *stream, char *buffer, size_t len);

	/**

	 * Write `len` bytes from `buffer` into the stream.

	 */

	int (*write)(git_odb_stream *stream, const char *buffer, size_t len);

	/**

	 * Store the contents of the stream as an object with the id

	 * specified in `oid`.

	 *

	 * This method might not be invoked if:

	 * - an error occurs earlier with the `write` callback,

	 * - the object referred to by `oid` already exists in any backend, or

	 * - the final number of received bytes differs from the size declared

	 *   with `git_odb_open_wstream()`

	 */

	int (*finalize_write)(git_odb_stream *stream, const git_oid *oid);

	/**

	 * Free the stream's memory.

	 *

	 * This method might be called without a call to `finalize_write` if

	 * an error occurs or if the object is already present in the ODB.

	 */

	void (*free)(git_odb_stream *stream);

};

/** A stream to write a pack file to the ODB */

struct git_odb_writepack {

	git_odb_backend *backend;

	int (*append)(git_odb_writepack *writepack, const void *data, size_t size, git_transfer_progress *stats);

	int (*commit)(git_odb_writepack *writepack, git_transfer_progress *stats);

	void (*free)(git_odb_writepack *writepack);

};

GIT_END_DECL

#endif